1. Field of the Invention (Technical Field)
The invention relates to nuclear reactors for use in space and more particularly to those which can be fueled, emptied and refueled in space and which incorporate redundancy and which are safe to launch and operate.
2. Description of the Related Art Including Information Disclosed under 37 C.F.R. .sctn..sctn.1.97-1.99 (Background Art)
Solid core reactors, currently proposed for space power applications, have a single core structure with inlet and outlet coolant ducts. Such designs have the disadvantages of a single point failure, since a break in or rupture of a single pipe feeding or removing coolant from the core would result in a complete loss of coolant. Subsequently, heat generated by the radioactive decay of fission products would overheat the core structure beyond its design limit and might melt the core in the absence of an auxiliary core cooling system. Some designs employ an independent auxiliary cooling loop to remove the decay heat from the core in case of a failure of the primary loop. Although employing an auxiliary loop could avoid degradation of the core structure due to overheating, it increases the size and mass of the core and requires a complete shutdown of the reactor, thereby terminating the mission. An early termination will naturally result in significant losses in resources and scientific opportunities.
Another drawback of current solid core reactors is the need for at least two independent safety mechanisms, each of which is capable of shutting down the reactor during emergency. With these safety mechanisms in place, reactors are designed to remain subcritical during a launch abort resulting in a water immersion or core compaction.